One or more prime movers used in a given application or system environment may be sized to provide power to support the greatest load that may be encountered during operation. For example, in connection with an aircraft (e.g., an airplane or helicopter) that includes two engines or turbines, each of the engines may be sized for worst-case loads to support the aircraft on its own for a short period of time in order to provide for safe operation.
Sizing an engine to support worst-case loads adversely impacts fuel efficiency for other power conditions. For example, sizing an engine for emergency conditions results in sub-optimal specific fuel consumption during cruise operation, increasing the amount of fuel consumption per unit of power produced. An engine will operate at significantly reduced fuel efficiency relative to the engine's optimum capability for the majority of its operating life.